Tastes in wine: fermentation

The Secret Life of Wine #30

Jesus drank wine but I’m pretty sure it was because he didn’t trust the water. He is, as far as I know, the world’s best-known winemaker. Sadly, his techniques have proven difficult to replicate.

Today, Jesus would have 47 media consultants and the Virgin Mary telling him that if he had the business savvy of an asparagus he would turn the wine into water instead of the other way around. Bottled water sells way better than bottled wine. And, at a much bigger profit.

Fermentation effects on wine taste

Learning what causes different tastes in wine is the Level 2 skill that naturally has its foundation in the Level 1 skill of identifying a wine’s sensory components. If you can’t recognize the smells, colors, tastes and mouthfeel of a wine then obviously you’re not going to be able to learn what causes them— the vanilla taste from barrels for instance or the texture of a Chardonnay that has gone through malolactic fermentation.

Given his father’s connections, Jesus didn’t have to ferment grapes to make wine. But, the rest of us do. Letting the yeast in the air work on the sugar in the juice mysteriously transforms it into alcohol even if you don’t do anything to it.

That’s why you can stomp on a bunch of grapes in the backyard and they start to ferment by themselves in the wading pool. Or, bucket. Or, as is still common in parts of the world, a cistern built for that purpose.

The fermentation of wine is fundamentally still as much a mystery to us now as it was to our ancestors 8,000 years ago when they first stumbled across fermenting clusters of grapes in the wild. Imagine their surprise.

Grapes ferment on the vine from the wild yeast in the air and the weight of their own clusters. Careful observation of the drunk vineyard starlings is always rewarding.

In the fall, especially late September and October, watching them trying to land on fence wires is not only entertaining, it’s free. You can even take videos if you like.

The Mystery of Fermentation

from Gay Lussac —fermentation chemical reaction - Pesquisa Google

The fierceness and general theatricality of fermentation made our ancestors believe that surely this must be the actual blood and body of God transforming the world right before their eyes.

Wine is produced when grapes are crushed and the natural sugar in the juice is turned into alcohol in the form of a thick bubbling, burping, roiling ocean of juice and yeast misted in a blanket of carbon dioxide gases that would give you pause even today. It certainly looks and smells like something other worldly is going on.

Chemists can diagram thousands of molecular interchanges during the process of turning grape juice into wine, set fermentation S-curves and harvest wine flavors like wheat in an open field, but not one of them can absolutely, definitively tell you what fermentation is, so I will tell you.

It’s a mystery is what it is.

Fermenting grapes at Rominger West Winery, Davis, California.

Click to visit Rominger West

Fermentation Recipes

Each winery has its own fermentation protocols—like a secret recipe. They all have their own yeasts plus whatever wild yeasts are on the property and in the air at the winery plus they have their own personal fermentation temperature curve.

Now ,while I like a hearty discussion of fermentation curves as much as the next guy, I’m going to skip that now and focus on the tastes in the wine.

The important point is that you can give the same grapes to three different wineries and you will get three different tasting wines.

Sugar turns into Alcohol + CO2

The fermentation process in wine basically occurs when grape sugars are acted on by yeasts which produces alcohol + CO2. I implore the chemists in the room to stay with me here. That’s actually the last part of a complicated process. I know it’s not that simple, but that’s the result.

And, one of the most anxiety inducing aspects of making wine is that fermentation can get stuck when the temperature is wrong or too many yeasts die off as carbon dioxide builds up in the closed tanks.

That’s why those stomped grapes in the backyard bucket don’t turn into Chateau Lafite. Without the temperature controlled tanks, and the right yeasts, fermentations in the wild tend to stop before they can convert significant amounts of sugar into alcohol.

Not always though. Backyard brews can go up to 14-15% alcohol under supervision, sometimes even higher if the emerging wine is fiddled with. Stuck fermentations are normal for backyard winemaking, but in a commercial winery they are a curse. They don’t happen very often because there are now all kinds of tricks to keep it going.

Winemakers watch the whole process closely. Lab equipment is involved. Computers with bright colors too. Stuck fermentations can send a winery to bankruptcy.

Fermentation Tastes

Bottle Fermentation: bubbles

Generally this is reserved for sparkling wines like Champagne. Sugar is added to the wine in the bottle and a secondary fermentation occurs. It’s not a thing I would fool with myself because sometimes the bottles explode under the mounting pressure. But, it’s great if you know what you’re doing.

Bubbles are the result of bottle fermentation so that’s easy to detect in sparkling wines—it defines them as sparkling wines.

But, there is also a bad kind of secondary fermentation in the bottle. It usually happens when semi-sweet or sweet wines, like say Vinho Verdi from Portugal or Albarino from Spain, get too hot somewhere along the way from vineyard to table.

A ring of tiny bubbles form around the edge of the wine in the glass. Beware. That ring of bubbles happens to red wines too. If you spot a tiny ring of bubbles around your glass, its probably a sign of sugar in the wine that started fermenting when the wine got too hot in shipping or storage.

Carbonic Maceration: bright berry flavors

I just like dropping “carbonic maceration” into random conversations when I run out of things to say. It is a fermentation that occurs within the grapes themselves instead of relying on yeast in the tank or barrel. It’s a basic technique of French Beaujolais and of some American Gamays. It has an intense berry smell and low tannins. Once you learn it, you can pick it out and amaze your friends.

“Fermented inside the grapes,” you’ll say. “under a carbon dioxide blanket. I’ll wager. Probably Gamay, ” you’ll say.

Most people will then walk away and leave you alone.

Malolactic Fermentation: creamier mouthfeel

This is a technique often used in California Chardonnays and French Burgundies. Certain yeasts, like Saccharomyces cerevisiae strain ML01, are introduced into the barrel and they induce enzymes that convert malic acid into lactic acid. Lactic acid is what makes your body hurt when you run too far.

Of course, I had to look up the name of that yeast.

I’m not even getting into the enzyme names and permease. You should be glad, it’s a slippery slope. Once you start naming yeasts there’s no end to it.

From a tasting standpoint, malolactic creates a “creamier” softer edge, especially to high alcohol Chardonnay. It’s primarily a mouthfeel thing.

This is all a lot harder than the way Jesus did it. And, more expensive. And, it takes a lot longer. But, until someone figures out how to turn water directly into wine, we’re stuck with fermentation.

I included this because it’s such a clear video on the harvesting, pressing and fermenting grapes. The visuals are great. I don’t know anything about Bolney itself.

How Wine is Made. Bolney Wine Estate, England. from “Insider"